What causes "line {line_number}: squash requires at least two commits" in gitbutlerapp/gitbutler?

Keep at least two commits on the line: `squash 4f2a9c1 991b3aa`.

gitbutlerapp/gitbutler · error · anyhow::Error

line {line_number}: squash requires at least two commits

Error message

line {line_number}: squash requires at least two commits

What it means

Raised by `parse_integration_steps_script` when a `squash` line lists fewer than two commit specs. Squash exists solely to combine multiple commits, so a single-commit squash is rejected at parse time.

Source

Thrown at crates/but-workspace/src/branch/integrate_branch_upstream/parsing.rs:79

                if message_part.is_some() {
                    bail!("line {line_number}: merge does not accept a message clause");
                }
                if arguments.len() != 1 {
                    bail!("line {line_number}: merge requires exactly one commit");
                }
                let commit = arguments
                    .first()
                    .copied()
                    .expect("validated merge arity above");
                InteractiveIntegrationStep::Merge {
                    commit_id: resolve_commit(commit, &allowed_commits).map_err(|err| {
                        anyhow::anyhow!("line {line_number}: invalid merge commit: {err}")
                    })?,
                }
            }
            "squash" => {
                if arguments.len() < 2 {
                    bail!("line {line_number}: squash requires at least two commits");
                }
                let commits = arguments
                    .iter()
                    .map(|commit| {
                        resolve_commit(commit, &allowed_commits).map_err(|err| {
                            anyhow::anyhow!(
                                "line {line_number}: invalid squash commit '{commit}': {err}"
                            )
                        })
                    })
                    .collect::<Result<Vec<_>>>()?;
                InteractiveIntegrationStep::Squash {
                    commits,
                    message: message_part
                        .map(parse_message_clause)
                        .transpose()
                        .map_err(|err| {
                            anyhow::anyhow!("line {line_number}: invalid squash message: {err}")

View on GitHub (pinned to caf1f223d3)

Solutions

Keep at least two commits on the line: `squash 4f2a9c1 991b3aa`.
If only one commit should remain, replace the squash line with `pick <sha>`.
If the group should vanish entirely, delete the whole line.

Example fix

# before
squash 4f2a9c1

# after
pick 4f2a9c1

Defensive patterns

Strategy: validation

Try / catch

if let Err(err) = parse_integration_steps_script(&script, &divergence) {
    // 'line {n}: squash requires at least two commits'
    // suggest replacing the line with 'pick <sha>' or deleting it
}

Prevention

When the UI lets users remove commits from a squash group, auto-collapse groups of 1 into a pick line.
Validate the script with the parser before integration.

When it happens

Trigger: Script line `squash 4f2a9c1` (one commit) or `squash` (none). Often the result of a user deleting one of the commits from a pre-filled squash group.

Common situations: User removes a commit from a squash group the proposal generated, leaving one behind; or intends 'squash into nothing' semantics that the model doesn't have.

Related errors

AI-assisted analysis of gitbutlerapp/gitbutler@caf1f223d3 (2026-08-20). Data as JSON: /api/errors/98b1ef80aa80a59f. Report an issue: GitHub.